Process for the preparation of o/w or o/w/o emulsions and 0/w and o/w/o emulsions obtainable by such processes

ABSTRACT

O/W emulsions, in particular O/W microemulsions, or O/W/O emulsions or O/W/O′ emulsions comprising at least one emulsifier (emulsifier A) chosen from the group of emulsifiers having the following properties  
     their lipophilicity either depends on the pH such that the lipophilicity is increased or decreased by raising or lowering the pH, it being unimportant which of the two possible changes in lipophilicity is effected by increasing or lowering the pH, and/or  
     their lipophilicity depends on the temperature such that the lipophilicity increases with increasing temperature and their hydrophilicity increases with decreasing temperature.

[0001] The present invention relates to stable emulsions of the O/W orO/W/O or O/W/O′-type, processes for their preparation and their use forcosmetic and medicinal purposes.

[0002] Cosmetic skin care is primarily to be understood as meaning thatthe natural function of the skin as a barrier against environmentalinfluences (for example dirt, chemicals, microorganisms) and against theloss of endogenous substances (for example water, natural fats,electrolytes) is intensified or re-established.

[0003] If this function is impaired, increased absorption of toxic orallergenic substances or attack by microorganisms and, as a result,toxic or allergic skin reactions may occur.

[0004] One aim of skin care is furthermore to compensate the loss offats and water from the skin due to daily washing. This is importantprecisely if the natural capacity for regeneration is not adequate. Skincare products should furthermore protect against environmentalinfluences, in particular against sun and wind, and delay ageing of theskin.

[0005] Medicinal topical formulations as a rule comprise medicaments inan active concentration. For simplicity, for clear differentiationbetween cosmetic and medicinal use and corresponding products, referenceis made to the legal provisions of the Federal Republic of Germany (forexample cosmetics legislation, food and medical preparations law).

[0006] It is known that multiple emulsions—inter alia—can bedistinguished by a particularly fine emulsion texture. This propertyrenders them outstandingly suitable as a basis both for cosmetic and formedicinal topical formulations. However, where cosmetics are used onlyexternally, all the customary modes of administration, for example oraladministration forms, are conceivable in the case of medicinal use ofemulsions.

[0007] In simple emulsions, one phase comprises finely disperse dropletsof the second phase enclosed by an emulsifier shell (water droplets inW/O or lipid vesicles in O/W emulsions). In a multiple emulsion (of thesecond degree), on the other hand, more finely disperse droplets of thefirst phase are emulsified in such droplets. In turn, even more finelydisperse droplets can also be present in these droplets (multipleemulsion of the third degree) and so on.

[0008] Thus, as W/O or O/W emulsions (water-in-oil or oil-in-water) arereferred to in the case of simple emulsions, in the case of multipleemulsions there are W/O/W, O/W/O, O/W/O/W, W/O/W/O emulsions and so on.

[0009] Multiple emulsions in which the particular internal and externalaqueous phases or internal and external oily phases are of a differenttype (that is to say, for example, W/O/W′ and O/W/O′ emulsions) can beprepared by two-pot processes. Those emulsions in which the internal andexternal aqueous and oily phases are not of a different type areobtainable both by one-pot and by two-pot processes.

[0010]FIG. 1 shows a diagram of an O/W/O emulsion, in which the whiteareas are the external and internal oily phase and the shaded areas arethe aqueous phase. It has not been specified whether the compositions ofthe external and internal oily phase differ from one another, that is tosay whether an O/W/O or an O/W/O′ emulsion is present.

[0011] Multiple emulsions of the second degree are occasionally called“bimultiple systems”, those of the third degree are occasionally called“trimultiple systems” and so on (W. Seifriz, Studies in Emulsions, J.Phys. Chem., 29 (1925) 738-749).

[0012] The expert is familiar per se with processes for the preparationof multiple emulsions. Thus, there are two-pot processes in which asimple emulsion (for example a W/O emulsion) is initially introducedinto the preparation vessel and is converted into a multiple emulsion(for example a W/O/W emulsion) by addition of another phase (for examplean aqueous phase) with a corresponding emulsifier (for example an O/Wemulsifier).

[0013] A second known process comprises converting emulsifier mixtureswith an oily phase and an aqueous phase into a multiple W/O/W emulsionin a one-pot process. The emulsifiers are dissolved in the oily phaseand the solution is combined with the aqueous phases A pre-requisite forsuch a process is that the HLB values (HLB=hydrophilic-lipophilicbalance) of the individual emulsifiers employed differ significantlyfrom one another.

[0014] The definition of the HLB value for polyol fatty acid esters isgiven by the formula I

HLB=20×(1−H/A)

[0015] For a group of emulsifiers in which the hydrophilic contentcomprises only ethylene oxide units, formula II applies

HLB=E/5

[0016] where

[0017] H=hydrolysis number of ester,

[0018] A=acid number of the acid recovered

[0019] E=weight content of ethylene oxide (in %) in the total molecule.

[0020] Emulsifiers with HLB values of 6-8 are in general W/Oemulsifiers, and those with HLB values of 8-18 are in general O/Wemulsifiers. Literature: “Kosmetik—Entwicklung, Herstellung undAnwendung kosmetischer Mittel” [Cosmetics—Development, Preparation andUse of Cosmetic Composition]; W. Umbach (editor), Georg Thieme Verlag1988.

[0021] Hydrophilic emulsifiers (with high HLB values) are as a rule O/Wemulsifiers. Accordingly, hydrophobic or lipophilic emulsifiers (withlow HLB values) are as a rule W/O emulsifiers.

[0022] U.S. Pat. Specification No. 4,931,210 describes a process for thepreparation of W/O/W emulsions in which polyglycerol polyricinoleatesare used as emulsifiers.

[0023] Although multiple emulsions are thus known per se and there areentirely simple processes for their preparation, there has neverthelessto date been a lack of such systems which are stable microscopicallyover relatively long storage times (for example for several years) or ina wide temperature range (for example from −10° C. to +50° C.) or toextreme variations in temperature (stable to swings, for example, from−15 to +50° C.). This means that the multiple emulsions of the prior artare converted into simple W/O or O/W emulsions in the course of time,that is to say have a low storage stability in the sense ofmultiplicity. This is a particular disadvantage, since these conversionproducts as a rule have an extremely inhomogeneous droplet sizedistribution.

[0024] At best, such conversion products are unattractive, or inelegantfrom the cosmetic aspect. However, the inhomogeneous size distributionof the droplets is often also associated with a lack of macroscopicstability, that is to say stability to decomposition into separatephases.

[0025] In this respect also, the conventional multiple emulsions werealways either inadequately stable, or transfer from the laboratory scaleto large-scale production could not be implemented.

[0026] The lack of O/W/O emulsions is a particular disadvantage, sinceW/O/W emulsions are usually described in the published prior art.Cosmetic or dermatological O/W/O emulsions are currently ratherlaboratory specialities than products obtainable on the market.

[0027] The droplet diameters of the usual “simple”, that is to saynon-multiple, emulsions are in the range from about 1 μm to about 50 μm.Without further colouring additives, such “macroemulsions” are milkywhite in colour and opaque. Finer “macroemulsions”, the dropletdiameters of which are in the range from about 10⁻¹ μm to about 1 μm,again without colouring additives, are bluish white in colour andopaque. Such “macroemulsions” usually have a high viscosity.

[0028] A clear and transparent appearance is reserved for micellar andmolecular solutions with particle diameters of less than about 10⁻² μm,but these are no longer to be interpreted as true emulsions.

[0029] The droplet diameter of microemulsions, on the other hand, is inthe range from about 10⁻² μm to about 10⁻¹ μm. Microemulsions aretranslucent and usually of low viscosity. The viscosity of manymicroemulsions of the O/W type is comparable to that of water.

[0030] An advantage of microemulsions is that active compounds can bepresent in the disperse phase in a considerably more finely disperseform than in the disperse phase of “macroemulsions”. Another advantageis that, because of their low viscosity, they can be sprayed. Ifmicroemulsions are used as cosmetics, corresponding products aredistinguished by a high cosmetic elegance.

[0031] A disadvantage of the microemulsions of the prior art is that ahigh content of one or more emulsifiers must always be employed, sincethe small droplet size results in a high interface between the phases,which as a rule must be stabilized by emulsifiers.

[0032] Because of their good sprayability, microemulsions are inprinciple also suitable for other cosmetic dermatological uses, forexample deodorants, so that, in a particular embodiment, the presentinvention relates to microemulsions as a base for cosmetic deodorants.

[0033] Cosmetic deodorants serve to eliminate body odour which formswhen fresh perspiration, which is odourless per se, is decomposed bymicroorganisms. The customary cosmetic deodorants are based on differentaction principles.

[0034] In so-called antiperspirants, the formation of perspiration canbe reduced by astringents—chiefly aluminium salts, such as aluminiumhydroxychloride (aluminium chlorohydrate).

[0035] The bacterial flora on the skin may be reduced by the use ofantimicrobial substances in cosmetic deodorants. In the ideal case, onlythe microorganisms which cause odour should be effectively reduced here.The flow of perspiration itself is not influenced as a result, and inthe ideal case only the microbial decomposition of the perspiration istemporarily stopped.

[0036] The combination of astringents with substances having anantimicrobial action in one and the same composition is also customary.

[0037] Deodorants should meet the following conditions:

[0038] 1) They should have the effect of reliable deodorizing.

[0039] 2) The natural biological processes of the skin should not beimpaired by the deodorants.

[0040] 3) In the event of an overdose or if otherwise used not asintended, the deodorants must be harmless.

[0041] 4) They should not accumulate on the skin after repeated use.

[0042] 5) They should be easy to incorporate into customary cosmeticformulations.

[0043] Both liquid deodorants, for example aerosol sprays, roll-ons andthe like, and solid formulations, for example deodorant sticks, powders,powder sprays, intimate cleansing compositions and the like, are knownand customary.

[0044] Although the conventional formulations in emulsion form ingeneral have a good action, they are distinguished to only a limitedextent by a care action. The use of microemulsions as a base fordeodorizing formulations or formulations having an antiperspirant actionis also known. Their relative high content of emulsifiers with thedisadvantages described has to date been a poor state of affairs whichis to be remedied.

[0045] Another object of the present invention was thus to developformulations which are suitable as a base for cosmetic deodorants orantiperspirants and do not have the disadvantages of the prior art.

[0046] It was furthermore an object of the invention to develop cosmeticbases for cosmetic deodorants which are distinguished by a good skintolerance.

[0047] It was moreover an object of the present invention to provideproducts based on microemulsions or O/W/O emulsions having the broadestpossible diversity of use. For example, bases for formulation forms suchas cleansing emulsions, face and body care formulations, and alsodecidedly medicinal-pharmaceutical presentation forms should beprovided, for example formulations against acne and other pathologicalskin symptoms. Finally, the route to emulsions which can be usedinternally, for example for parenteral feeding, should also be opened upin principle by the present invention.

[0048] A particular object of the present invention was to providefinely disperse formulations of the oil-in-water type or multipleemulsions of the O/W/O type having the lowest possible emulsifiercontent which do not have the disadvantages of the prior art and can beused for the most diverse cosmetic and/or dermatological uses, forexample the uses described above. Another object of the invention was toenrich the limited range of finely disperse formulations of theoil-in-water type of the prior art.

[0049] It is known that hydrophilic emulsifiers change their solubilityproperties from water-soluble to fat-soluble with increasingtemperature. The temperature range in which the emulsifiers have changedtheir solubility is called the phase inversion temperature range (PIT).

[0050] S. Matsumoto (Journal of Colloid and Interface Science, Volume94, No. 2, 1983) reports that the development of a W/O/W emulsionprecedes a phase inversion of concentrated W/O emulsions stabilized bySpan 80, a pronounced W/O emulsifier. Matsumoto starts here from anextremely non-polar oil, that is to say liquid paraffin. Moreover, acertain amount of hydrophilic emulsifiers is said to be necessary fordevelopment of a W/O/W emulsion from a W/O emulsion.

[0051] T. J. Lin, H. Kurihara and H. Ohta (Journal of the Society ofCosmetic Chemists 26, pages 121-139, March 1975) show that in the caseof non-polar oils, extremely unstable multiple emulsions can be presentin the region of the PIT.

[0052] Microemulsions can also be prepared via phase inversiontechnology. However, microemulsions of the prior art prepared in such amanner have the disadvantage that firstly the droplet size is stillquite high, and secondly a high content of one or more emulsifiers isstill necessary.

[0053] It is furthermore a disadvantage that although microemulsionsprepared in such a manner are practically transparent at a hightemperature, that is to say, for example, in the PIT, they becometranslucent or opaque again on falling to room temperature.

[0054] These poor states of affairs were thus also to be remedied.

[0055] The object of the present invention was thus to provide stablemicroemulsions of the O/W type or stable multiple emulsions of the O/W/Oor O/W/O′ type and to eliminate the disadvantages of the formulations ofthe prior art and of their preparation processes.

[0056] It has been found, surprisingly, and this accounts for theachievement of the objects, that O/W emulsions, in particular O/Wmicroemulsions, or O/W/O emulsions or O/W/O′ emulsions comprising

[0057] an aqueous phase,

[0058] if appropriate, customary water-soluble or -dispersiblesubstances,

[0059] an oily phase,

[0060] at least one emulsifier (emulsifier A) chosen from the group ofemulsifiers having the following properties

[0061] their lipophilicity either depends on the pH such that thelipophilicity is increased or decreased by raising or lowering the pH,it being unimportant which of the two possible changes in lipophilicityis effected by raising or lowering the pH, and/or

[0062] their lipophilicity depends on the temperature such that thelipophilicity increases with increasing temperature and theirhydrophilicity increases with decreasing temperature,

[0063] and furthermore, if appropriate, further substances which aresoluble or dispersible in the oily phase, including, preferably, thosechosen from the group of emulsifiers which do not fall under thedefinition of emulsifier A, in particular those which chiefly act as W/Oemulsifiers,

[0064] remedy the disadvantages of the prior art.

[0065] An advantageous embodiment of the present invention is also aprocess for the preparation of o/W emulsions, in particular O/Wmicroemulsions, or O/W/O emulsions or O/W/O′ emulsions, characterized inthat an aqueous phase, if appropriate, customary water-soluble or

[0066] dispersible substances, an oily phase and

[0067] at least one emulsifier (emulsifier A) chosen from the group ofO/W emulsifiers having the following properties

[0068] their lipophilicity depends on the pH such that the lipophilicityis increased or decreased by raising or lowering the pH, it beingunimportant which of the two possible changes in lipophilicity iseffected by raising or lowering the pH, and

[0069] if appropriate, their lipophilicity additionally depends on thetemperature such that the lipophilicity increases with increasingtemperature and their hydrophilicity increases with decreasingtemperature,

[0070] and furthermore, if appropriate, further substances which aresoluble or dispersible in the oily phase, including, preferably, thosechosen from the group of emulsifiers which do not fall under thedefinition of emulsifier A, are brought together and a mixture isformed, with agitation, such that

[0071] by suitable choice of the parameters chosen from the groupconsisting of pH, temperature and the concentration or concentrations ofat least one of the emulsifiers chosen, this mixture is brought into thephase inversion range in which W/O emulsions are converted into O/Wemulsions,

[0072] by varying at least one parameter chosen from the groupconsisting of pH, temperature and the concentration or concentrations ofat least one of the emulsifiers chosen, the W/O emulsion formed isbrought out of the phase inversion range in which a W/O emulsion formedis converted into an O/W emulsion, whereupon an O/W emulsion or O/Wmicroemulsion is produced,

[0073] if appropriate, by suitable choice of the framework conditions,another phase inversion to give an O/W/O emulsion is initiated,

[0074] if appropriate, the mixture is subjected to further processingsteps, in particular one or more homogenizing steps.

[0075] Processes which are equally advantageous according to theinvention are those in which the variation in the parameter orparameters comprises a procedure in which

[0076] (a) at a given pH and given concentration of emulsifier A or ofthe plurality of emulsifiers A, the temperature of the mixture and, ifappropriate, additionally the concentration of at least one furtheremulsifier A is varied, in which

[0077] (b) at a given temperature and given concentration of emulsifierA or of the plurality of emulsifiers A, the pH of the mixture and, ifappropriate, additionally the concentration of at least one furtheremulsifier A is varied, in which

[0078] (c) at a given temperature and given pH, the concentration of atleast one emulsifier A and, if appropriate, additionally theconcentration of at least one further emulsifier A is varied, in which

[0079] (d) at a given pH, the temperature of the mixture andadditionally the concentration of at least one emulsifier A and, ifappropriate, additionally the concentration of at least one furtheremulsifier A are varied, in which

[0080] (e) at a given temperature of the mixture, the pH of the mixtureand additionally the concentration of at least one emulsifier A and, ifappropriate, additionally the concentration of at least one furtheremulsifier A are varied, and in which

[0081] (f) at a given concentration of at least one emulsifier A, the pHand additionally the temperature of the mixture and, if appropriate,additionally the concentration of at least one further emulsifier A arevaried.

[0082] If the phase inversion is essentially initiated by varying thetemperature, O/W emulsions, in particular O/W microemulsions, areobtainable, the size of the oil droplets essentially being determined bythe concentration of the emulsifier or emulsifiers employed such that ahigher emulsifier concentration has the effect of smaller droplets and alower emulsifier concentration leads to larger droplets. If the phaseinversion is essentially initiated by varying the temperature, it isentirely advantageous to dispense with further emulsifiers which do notfall under the definition of emulsifier A, that is to say W/Oemulsifiers.

[0083] If the phase inversion is essentially initiated by varying thepH, O/W emulsions, in particular O/W microemulsions, and also O/W/Oemulsions are obtainable. If the phase inversion is essentiallyinitiated by varying the pH, it is entirely advantageous to employ oneor more further emulsifiers which do not fall under the definition ofemulsifier A, that is to say W/O emulsifiers.

[0084] O/W/O emulsions can be obtained according to the invention if theoily phase content is greater than about 15% by weight, in particulargreater than about 20% by weight, based on the total weight of theformulation, more than about 5% by weight, in particular about 5-10% byweight, of an additional W/O emulsifier which does not fall under thedefinition of emulsifier A is present, and/or if the oily phase has alow content of polar oils.

[0085] O/W microemulsions can be obtained according to the invention ifthe oily phase content is less than about 20% by weight, in particularless than about 15% by weight, based on the total weight of theformulation, less than about 5% by weight of an additional W/Oemulsifier which does not fall under the definition of emulsifier A ispresent, and/or if the oily phase has a high content of polar oils.

[0086] O/W emulsions (“macroemulsions”) can be obtained according to theinvention if less than about 5% by weight of an additional W/Oemulsifier which does not fall under the definition of emulsifier A andmore than about 20% by weight of a polar oily phase are present.Additional gel-forming agents (for example carbopols, xanthan gum,cellulose derivatives) can advantageously be employed.

[0087] In the individual case, it is possible that the concentrationeasily exceeds or falls below the above-mentioned limits, andnevertheless the emulsion types in question are obtained. In view of thewide-ranging diversity of suitable emulsifiers and oil constituents,this is not unexpected to the expert, so that he knows that suchexcesses or deficits do not leave the basis of the present invention.

[0088] The phase inversion range can be demonstrated mathematically as apoint quantity within the straight-line coordinate system Σ formed bythe parameters of temperature, pH and concentration of a suitableemulsifier or of an emulsifier mixture in the formulation, in accordancewith:

Σ={O, θ, a, m}

[0089] where

[0090] O—coordinate origin

[0091] θ—temperature

[0092] a—pH

[0093] m—concentration

[0094] In precise terms, in a multi-component emulsifier system, theamount m_(i) of each individual emulsifier must of course be taken intoaccount to give the total function, which, in the case of an i-componentemulsifier system, leads to the relationship

Σ={O, θ, a, m₁, m₂, . . . , m_(i)}.

[0095] The phase inversion range Φ in the mathematical sense here is acontinuous region or a plurality of continuous regions within thecoordinate system Σ. Φ represents the total amount of coordinate pointsK (θ, a, m₁, m₂, . . . , m_(i)) which determine mixtures according tothe invention of an aqueous and oily phase and i emulsifiers accordingto the invention of concentration m_(i) at the temperature θ and the pHa, and for which phase inversion occurs on transition from onecoordinate K₁ ∉ Φ to a coordinate K₂ ε Φ, as described in FIG. 2. Thetemperature and pH of a given mixture keeping the concentration ofm₁=m_(i) constant have been shown as variable coordinates in FIG. 2. Ontransition from K₁ to K₂, only the temperature is increased.

[0096] Under the conditions according to the invention, this process isnot reversible, i.e. if the system reverts from coordinate K₂ ε Φ backto coordinate K₁ ∉ Φ, other types of emulsion than would have beenexpected from the prior art can be obtained according to the invention.For example, if, by increasing the temperature of a mixture according tothe invention of aqueous and oily phase and i emulsifiers according tothe invention of concentrations m_(i), the pH a remaining constant,starting from a temperature which is too low for phase inversion (thatis to say conditions where a conventional O/W emulsion would be presentand would also remain as such on cooling to room temperature), thesystem is heated such that phase inversion occurs, after cooling, forexample to room temperature, no conventional O/W emulsion but an O/Wmicroemulsion according to the invention is obtained. Alternatively,mutatis mutandis: an O/W/O emulsion according to the invention.

[0097] It is unimportant here whether the phase inversion range of agiven system is a single continuous (i+2)-dimensional region orcomprises several such regions which are continuous but separate fromone another, i.e. corresponding to several phase inversion ranges of agiven system. In the context of the disclosure submitted here, one phaseinversion range is therefore always referred to as a generalization,even if two or more such ranges which are separate from one anotherexist.

[0098] The practice of preparation of an emulsion according to theinvention advantageously comprises a procedure in which, after selectionof suitable raw materials, i.e. the aqueous and oily phase, one or moreemulsifiers of type A, the latter present in concentrations at whichphase inversion for the given mixture is possible, and, if appropriate,further substances, the individual components are heated, withagitation, to a temperature at which phase inversion is possible for thegiven mixture, and phase inversion is brought about by raising orlowering the pH of the mixture, after which the mixture is allowed tocool to room temperature, while continuing agitation. One or moreintermediate homogenization steps are advantageous but not absolutelynecessary.

[0099] Another advantageous embodiment of the process according to theinvention comprises a procedure in which, after selection of suitableraw materials, i.e. the aqueous and oily phase, one or more emulsifiersof type A, the latter present in concentrations at which phase inversionfor the given mixture is possible, and, if appropriate, furthersubstances, the individual components are brought, with agitation, to apH at which phase inversion is possible for the given mixture, and phaseinversion is brought about by increasing the temperature of the mixture,after which the mixture is allowed to cool to room temperature, whilecontinuing agitation. One or more intermediate homogenization steps areadvantageous but not absolutely necessary.

[0100] A third advantageous embodiment of the process according to theinvention comprises a procedure in which, after selection of suitableraw materials, i.e. the aqueous and oily phase, one or more emulsifiersof type A and, if appropriate, further substances, the individualcomponents are brought, with agitation, to a pH and a temperature atwhich phase inversion is possible for the given mixture, and phaseinversion is brought about by addition of emulsifier A or emulsifiers Ato the mixture, after which the mixture is allowed to cool to roomtemperature, while continuing agitation. One or more intermediatehomogenization steps are advantageous but not absolutely necessary.

[0101] In practice, it is possible and, where appropriate, evenadvantageous for the temperature range which can be assigned to thephase inversion range also to be exceeded during preparation of anemulsion according to the invention, since the mixture necessarilypasses through this range on cooling to room temperature.

[0102] The emulsifiers A are preferably chosen from the group consistingof emulsifiers which are good proton donors or proton acceptors, whereit must be ensured that their lipophilicity depends on the pH such thatthe lipophilicity is increased or decreased by raising or lowering thepH, it being unimportant in principle which of the two possible changesin lipophilicity is effected by raising or lowering the pH, and, ifappropriate, their lipophilicity additionally depends on the temperaturesuch that their lipophilicity increases with increasing temperature andtheir hydrophilicity increases with decreasing temperature.

[0103] The lipid phase can advantageously be chosen from the followinggroup of substances:

[0104] oils, such as triglycerides of capric or of caprylic acid

[0105] fats, waxes and other naturally occurring and synthetic fatsubstances, preferably esters of fatty acids with alcohols of low Cnumber, for example with isopropanol, propylene glycol or glycerol, oresters of fatty alcohols with alkanoic acids of low C number or withfatty acids; and

[0106] alkyl benzoates.

[0107] The lipid phase can especially advantageously be chosen from thegroup consisting of silicone oils, such as dimethylpolysiloxanes,diethylpolysiloxanes, diphenylpolysiloxanes and mixed forms of these.

[0108] If appropriate, the aqueous phase of the formulations accordingto the invention advantageously comprises

[0109] alcohols, diols or polyols of low C number and ethers thereof,preferably ethanol, isopropanol, propylene glycol, glycerol, ethyleneglycol, ethylene glycol monoethyl or monobutyl ether, propylene glycolmonomethyl, monoethyl or monobutyl ether, diethylene glycol monomethylor monoethyl ether and analogous products, furthermore alcohols of low Cnumber, for example ethanol, isopropanol, 1,2-propanediol and glycerol,and, in particular, one or more thickeners, which can advantageously bechosen from the group consisting of silicon dioxide, aluminiumsilicates, polysaccharides and derivatives thereof, for examplehyaluronic acid, xanthan gum and hydroxypropylmethylcellulose,particularly advantageously from the group consisting of polyacrylates,preferably a polyacrylate from the group consisting of so-calledcarbopols, for example carbopols of types 980, 981, 1382, 2984 and 5984,in each case individually or in combination.

[0110] The emulsifiers of type A are advantageously chosen from thegroup consisting of sorbitan esters and sucrose esters, in particular ofbranched and unbranched alkyl esters and alkenyl esters having carbonchains of 4-24 carbon atoms, preferably sorbitan stearate, sorbitanoleate, glycerylsorbitan stearate, sucrose monostearate, sucrosemonolaurate and sucrose palmitate.

[0111] The emulsifiers of type A can advantageously be chosen from thegroup consisting of monoglycerol monocarboxylic acid monoesters, inparticular those which are characterized by the structures

[0112] wherein R is a branched or unbranched acyl radical having 6-14carbon atoms. R is advantageously chosen from the group consisting ofunbranched acyl radicals. The fatty acids or monocarboxylic acids onwhich these esters are based are hexanoic acid (caproic acid) (R =—C(O)—C₅H₁₁), heptanoic acid Coenanthic acid) (R = —C(O)—C₆H₁₃),octanoic acid (caprylic acid) (R = —C(O)—C₇H₁₅), nonanoic acid(pelargonic acid) (R = —C(O)—C₈H₁₇), decanoic acid (capric acid) (R =—C(O)—C₉H₁₉), undecanoic acid (R = —C(O)—C₁₀H₂₁), dodecanoic acidClauric acid) (R = —C(O)—C₁₁H₂₃), tridecanoic acid (R = —C(O)—C₁₂H₂₅),tetradecanoic acid (myristic acid) (R = —C(O)—C₁₃H₂₇).

[0113] R is particularly advantageously the octanoyl radical (caprylicacid radical) or the decanoyl radical (capric acid radical), that is tosay is represented by the formulae

R=—C(O)—C₇H₁₅ or R=—C(O)—C₉H₁₉.

[0114] Advantageously, the emulsifiers of type A can also be chosen fromthe group consisting of di- and triglycerol monocarboxylic acidmonoesters. According to the invention, the di- or triglycerol units ofthe diglycerol monocarboxylic acid monoesters or triglycerolmonocarboxylic acid monoesters according to the invention are present aslinear, unbranched molecules, that is to say “monoglycerol molecules”etherified via the particular OH groups in the 1- and 3-position.

[0115] A small content of cyclic di- or triglycerol units and glycerolmolecules etherified via the OH groups in the 2-position can betolerated. However, it is advantageous to keep such impurities as low aspossible.

[0116] The monocarboxylic acid monoesters according to the invention arepreferably characterized by the following structure (substitutionpositions shown):

[0117] wherein R′ is a hydrocarbon radical, advantageously a branched orunbranched alkyl or alkenyl radical having 5 to 17 C atoms.

[0118] The triglycerol monocarboxylic acid esters according to theinvention are preferably characterized by the following structure(substitution positions shown):

[0119] wherein R″ is a hydrocarbon radical, advantageously a branched orunbranched alkyl or alkenyl radical having 5 to 17 C atoms.

[0120] The acids on which these esters are based are hexanoic acid(caproic acid) (R′ or R″ = —C₅H₁₁), heptanoic acid (oenanthic acid) (R′or R″ = —C₆H₁₃), octanoic acid (caprylic acid) (R′ or R″ = —C₇H₁₅),nonanoic acid (pelargonic acid) (R′ or R″ = —C₈H₁₇), decanoic acid(capric acid) (R′ or R″ = —C₉H₁₉), undecanoic acid (R′ or R″ = —C₁₀H₂₁),10-undecenoic acid (undecylenic acid) (R′ or R″ = —C₁₀H₁₉), dodecanoicacid (lauric acid) (R′ or R″ = —C₁₁H₂₃) tridecanoic acid (R′ or R″ =—C₁₂H₂₅), tetradecanoic acid (myristic acid) (R′ or R″ = —C₁₃H₂₇),pentadecanoic acid (R′ or R″ = —C₁₄H₂₉), hexadecanoic acid (palmiticacid) (R′ or R″ = —C₁₅H₃₁), heptadecanoic acid (margaric acid) (R′ or R″= —C₁₆H₃₃), octadecanoic acid (stearic acid) (R′ or R″ = —C₁₇H₃₅).

[0121] R′ and R″ are particularly favourably chosen from the groupconsisting of unbranched alkyl radicals having odd C numbers, inparticular having 9, 11 and 13 C atoms.

[0122] The monocarboxylic acid monoesters of diglycerol are generallypreferable to those of triglycerol.

[0123] Especially favourable according to the invention are diglycerolmonocaprate (DMC) R′ =  9 triglycerol monolaurate (TML) R″ = 11diglycerol monolaurate (DML) R′ = 11 triglycerol monomyristate (TMM) R′= 13.

[0124] Diglycerol monocaprate (DMC) has proved to be the preferreddiglycerol monocarboxylic acid monoester according to the invention.

[0125] According to an advantageous embodiment of the present invention,an additional content of di- or triglycerol esterified at other points,and also optionally a content of the various diesters of di- ortriglycerol, are used.

[0126] Triglyceryl diisostearate (nomenclature analogous to CTFA:polyglyceryl 3-diisostearate), isostearyl-diglyceryl succinate,diglyceryl sesquiisostearate (nomenclature analogous to CTFA:polyglyceryl 2-sesquiisostearate), triglyceryl polyhydroxystearate(nomenclature analogous to CTFA: polyglyceryl 2-polyhydroxystearate) arealso advantageous.

[0127] Cetearyl isononanoate, dicocoylpentaenythrityl distearyl citrate,also the methicone copolyols, cyclomethicone copolyols, alkylimethicanecopolyols, especially laurylmethicone copolyol, cetyldimethiconecopolyol, have also proved advantageous according to the invention.

[0128] The emulsifier or emulsifiers of type A are especiallyadvantageously chosen from the group consisting of branched orunbranched alkylmonocarboxylic acids, alkenylmonocarboxylic acids andalkylenedicarboxylic acids having 4 to 30 carbon atoms, in particularstearic acid, oleic acid, succinic acid, hexanoic acid (caproic acid),heptanoic acid (oenanthic acid), octanoic acid (caprylic acid), nonanoicacid (pelargonic acid), decanoic acid (capric acid), undecanoic acid,undecenoic acid (undecylenic acid), dodecanoic acid (lauric acid),tridecanoic acid, tetradecanoic acid (myristic acid), pentadecanoicacid, hexadecanoic acid (palmitic acid), heptadecanoic acid (margaricacid), octadecanoic acid (stearic acid), isostearic acid and behenicacid. It is also advantageous to choose the emulsifiers A from the groupconsisting of cosmetically or pharmaceutically acceptable salts of theabovementioned carboxylic acids, in particular of the alkali metal,ammonium, monoalkylammonium, dialkylammonium, trialkylammonium andtetraalkylammonium salts.

[0129] The emulsifier or emulsifiers A are likewise particularlyadvantageously chosen from the group consisting of mono-, oligo- andpolyethoxylated compounds, in particular polyethoxylated mono- orpolyfunctional alcohols or fatty acids, for example ceteareth-20, PEG20-glyceryl stearate, steareth-20, PEG 20-stearate, PEG 30-stearate, PEG40-castor oil, PEG 1-glycerol sorbitan oleostearate, PEG 7-hydrogenatedcastor oil, PEG 40-sorbitan peroleate and PEG 45-dodecylglycolcopolymer.

[0130] The emulsions according to the invention are advantageouslycharacterized in that the emulsifier A or the emulsifiers A is or arepresent in concentrations of 0.01-20% by weight, preferably 0.05-10% byweight, particularly preferably 0.1-5% by weight, in each case based onthe total weight of the composition.

[0131] If the O/W/O emulsions or O/W microemulsions according to theinvention are bases for cosmetic deodorants/antiperspirants, all thecustomary active compounds can advantageously be used, for example odourmaskers, such as the customary perfume constituents, odour absorbers,for example the laminar silicates described in Patent Publication DE-P40 09 347, and of these in particular montmorillonite, kaolinite, ilite,beidellite, nontronite, saponite, hectorite, bentonite and smectite, andfurthermore, for example, zinc salts of ricinoleic acid. Germ-inhibitingagents are likewise suitable for incorporation into the microemulsionsaccording to the invention. Advantageous substances are, for example,2,4,4′-trichloro-2′-hydroxydiphenyl ether (irgasan),1,6-di(4-chlorophenylbiguanido)hexane (chlorhexidine),3,4,4′-trichlorocarbanilide, quaternary ammonium compounds, oil ofcloves, mint oil, oil of thyme, triethyl citrate, rarnesol(3,7,11-trimethyl-2,6,10-dodecatrien-1-ol) and the active agentsdescribed in DE-OS 37 40 186, DE-OS 39 38 140, DE-OS 42 04 321, DE-OS 4229 707, DE-OS 42 29 737, DE-OS 42 37 081, DE-OS 43 09 372 and DE-OS 4324 219.

[0132] The customary antiperspirant active compounds can likewiseadvantageously be used in the formulations according to the invention,in particular astringents, for example basic aluminium chlorides.

[0133] The cosmetic deodorants according to the invention can be in theform of aerosols, that is to say preparations which can be sprayed fromaerosol containers, squeeze bottles or by a pump device, or in the formof liquid compositions which can be applied by means of roll-on devices,but also in the form of formulations which can be applied from normalbottles and containers.

[0134] Suitable propellants for cosmetic formulations, for exampledeodorants, according to the invention which can be sprayed from aerosolcontainers are the customary known readily volatile liquefiedpropellants, for example hydrocarbons (propane, butane, isobutane),which can be employed by themselves or as a mixture with one another.Compressed air can also advantageously be used.

[0135] The expert of course knows that there are propellant gases whichare non-toxic per se and would be suitable in principle for the presentinvention, but which should nevertheless be omitted because of anunacceptable effect on the environment or other concomitantcircumstances, in particular chlorofluorohydrocarbons (CFCs).

[0136] In order to obtain low-viscosity microemulsions according to theinvention, in particular those which can be sprayed, it is particularlyadvantageous if the oily phase comprises constituents which have amelting point below 40° C. in the smallest possible amount, and in theideal case no such constituents.

[0137] The cosmetic formulations according to the invention can comprisecosmetic auxiliaries such as are usually used in such formulations, forexample preservatives, bactericides, substances having a deodorizingaction, antiperspirants, insect repellants, vitamins, agents forpreventing foaming, dyestuffs, pigments having a colouring action,thickeners, softening substances, humidifying and/or humectantsubstances, fats, oils, waxes or other customary constituents of acosmetic formulation, such as alcohols, polyols, polymers, foamstabilizers, electrolytes, organic solvents or silicone derivatives.

[0138] According to the invention, the formulations according to theinvention advantageously comprise one or more antioxidants. All thenaturally occurring, synthetic and/or semi-synthetic antioxidants whichare suitable or customary for cosmetic and/or dermatological uses can beused as favourable antioxidants which are nevertheless optionally to beused.

[0139] The antioxidants are particularly advantageously chosen from thegroup consisting of amino acids (for example glycine, histidine,tyrosine, tryptophan) and derivatives thereof, imidazoles (for exampleurocanic acid) and derivatives thereof, peptides, such as D,L-carnosine,D-carnosine, L-carnosine and derivatives thereof (for example anserine),carotenoids, carotenes (for example α-carotene, β-carotene, lycopene)and derivatives thereof, lipoic acid and derivatives thereof (forexample dihydrolipoic acid), aurothioglucose, propylthiouracil and otherthiols (for example thioredoxin, glutathione, cysteine, cystine,cystamine and the glycosyl, N-acetyl, methyl, ethyl, propyl, amyl, butyland lauryl, palmitoyl, oleyl, γ-linoleyl, cholesteryl and glycerylesters thereof) and salts thereof, dilauryl thiodipropionate, distearylthiodipropionate, thiodipropionic acid and derivatives thereof (esters,ethers, peptides, lipids, nucleotides, nucleosides and salts) andsulphoximine compounds (for example buthionine-sulphoximines,homocysteine-sulphoximine, buthionine-sulphones, penta-, hexa- andheptathionine-sulphoximine) in very low tolerated dosages (for examplepmol to μmol/kg), and furthermore (metal) chelating agents (for example60 -hydroxy-fatty acids, palmitic acid, phytic acid, lactoferrin),α-hydroxy acids (for example citric acid, lactic acid, malic acid),humic acid, bile acid, bile extracts, bilirubin, biliverdin, EDTA, EGTAand derivatives thereof, unsaturated fatty acids and derivatives thereof(for example γ-linolenic acid, linoleic acid, oleic acid), folic acidand derivatives thereof, ubiquinone and ubiquinol and derivativesthereof, vitamin C and derivatives (for example ascorbyl palmitate, Mgascorbyl phosphates, ascorbyl acetates), tocopherols and derivatives(for example vitamin E acetate), vitamin A and derivatives (for examplevitamin A palmitate) and coniferyl benzoate of benzoin resin, flavonesor flavonoids, rutic acid and derivatives thereof, ferulic acid andderivatives thereof, butylhydroxytoluene, butylhydroxyanisole,nordihydroguaiac resin acid, nordihydroguaiaretic acid,trihydroxybutyrophenone, uric acid and derivatives thereof, mannose andderivatives thereof, zinc and derivatives thereof (for example ZnO,ZnSO₄), selenium and derivatives thereof (for example seleniummethionine), stilbenes and derivatives thereof (for example stilbeneoxide, trans-stilbene oxide) and the derivatives of these activecompounds mentioned which are suitable according to the invention(salts, esters, ethers, sugars, nucleotides, nucleosides, peptides andlipids).

[0140] It is furthermore advantageous to add to the formulationsaccording to the invention enzymes, co-enzymes, in particular biotin orbiotin esters, and also other substances of this or a related type whichare customary in cosmetics and dermatology, for example activators, suchas citric acid.

[0141] It is advantageous according to the invention to employ in theformulations according to the invention additional oil-soluble UVAfilters and/or UVB filters in the lipid phase and/or water-soluble UVAfilters and/or UVB filters in the aqueous phase.

[0142] The formulations according to the invention can advantageouslyfurthermore comprise substances which absorb UV radiation in the UVBrange, the total amount of filter substances being, for example, 0.1% byweight to 30% by weight, preferably 0.5 to 10% by weight, in particular1 to 6% by weight, based on the total weight of the formulation, inorder to provide cosmetic formulations which protect the skin from theentire range of ultraviolet radiation. They can also be used assunscreen compositions.

[0143] Formulations according to the invention, for example in the formof a sunscreen cream, a sunscreen lotion or a sunscreen milk, areadvantageous and comprise, for example, the fats, oils, waxes and otherfat substances mentioned, as well as water.

[0144] The UVB filters can be oil-soluble or water-soluble. Advantageousoil-soluble UVB filter substances are, for example:

[0145] 3-benzylidenecamphor derivatives, preferably3-(4-methylbenzylidene)camphor and 3-benzylidenecamphor;

[0146] 4-aminobenzoic acid derivatives, preferably 2-ethylhexyl4-(dimethylamino)benzoate and amyl 4-(dimethylamino)benzoate;

[0147] esters of cinnamic acid, preferably 2-ethylhexyl4-methoxycinnamate and isopentyl 4-methoxycinnamate;

[0148] derivatives of benzophenone, preferably2-hydroxy-4-methoxybenzophenone,2-hydroxy-4-methoxy-4′-methylbenzophenone and2,2′-dihydroxy-4-methoxybenzophenone;

[0149] esters of benzylmalonic acid, preferably di (2-ethylhexyl)4-methoxybenzalmalonate;

[0150] 2,4,6-trianilino-(p-carbo-2′-ethyl-1′-hexyloxy)-1,3,5-triazine.

[0151] Advantageous water-soluble UVB filter substances are, forexample:

[0152] salts of 2-phenylbenzimidazole-5-sulphonic acid, such as itssodium, potassium or its triethanolammonium salt, and the sulphonic aciditself;

[0153] sulphonic acid derivatives of benzophenones, preferably2-hydroxy-4-methoxybenzophenone-5-sulphonic acid and salts thereof;

[0154] sulphonic acid derivatives of 3-benzylidenecamphor, such as, forexample, 4-(2-oxo-3-bornylidenemethyl)benzenesulphonic acid,2-methyl-5-(2-oxo-3-bornylidenemethyl)benzenesulphonic acid and saltsthereof.

[0155] The list of UVB filters mentioned which can be used incombination with the active compound combinations according to theinvention is of course not intended to be limiting.

[0156] It may also be advantageous to combine the combinations accordingto the invention with UVA filters which have usually been contained todate in cosmetic formulations. These substances are preferablyderivatives of dibenzoylmethane, in particular1-(4′-tert-butyl-phenyl)-3-(4′-methoxyphenyl)propane-1,3-dione and1-phenyl-3-(4′-isopropylphenyl)propane-1,3-dione. The invention alsorelates to these combinations and to formulations which comprise thesecombinations. The amounts used for the UVB combination can be employed.

[0157] It is furthermore advantageous to combine the active compoundcombinations according to the invention with further UVA and/or UVBfilters.

[0158] The total amount of UVA filter substances can advantageously be0.1% by weight to 30% by weight, preferably 0.5 to 10% by weight, inparticular 1 to 6% by weight, based on the total weight of theformulation, in order to provide cosmetic formulations which protect theskin from the entire range of ultraviolet radiation and in which thestinging of the α-hydroxycarboxylic acids or α-ketocarboxylic acids isprevented or drastically reduced.

[0159] Those cosmetic and dermatological formulations which are in theform of a sunscreen composition or a pre-soleil or apres-soleil productare also advantageous. Advantageously, these additionally comprise atleast one UVA filter and/or at least one UVB filter.

[0160] Those cosmetic and dermatological formulations which are in theform of a sunscreen composition or a pre-soleil or apres-soleil productand comprise one or more antioxidants in addition to the UVA filter orfilters and/or the UVB filter or filters are furthermore alsoadvantageous.

[0161] Cosmetic and dermatological formulations according to theinvention preferably comprise inorganic pigments based on metal oxidesand/or other metal compounds which are sparingly soluble or insoluble inwater, in particular the oxides of titanium (TiO₂), zinc (ZnO), iron(for example Fe₂O₃), zirconium (ZrO₂), silicon (SiO₂), manganese (forexample MnO), aluminium (Al₂O₃) or cerium (for example Ce₂O₃), mixedoxides of the corresponding metals and mixtures of such oxides. Thepigments are particularly preferably those based on TiO₂.

[0162] A prerequisite for the usability of inorganic pigments forpurposes according to the invention is of course cosmetic anddermatological acceptability of the substances on which they are based.

[0163] It is advantageous to choose the particle diameter of thepigments used at less than 100 nm.

[0164] According to the invention, the inorganic pigments are present inhydrophobic form, i.e. they have been given a water-repellent treatmenton the surface. This surface treatment can comprise providing thepigments with a thin hydrophobic layer by processes known per se.

[0165] Such a process comprises, for example, a procedure in which thehydrophobic surface layer is produced by a reaction according to nTiO₂+m (RO)₃Si—R′→n TiO₂ (surface). n and m here are stoichiometricparameters to be employed as desired and R and R′ are the desiredorganic radicals. Hydrophobized pigments prepared analogously to DE-OS33 14 742, for example, are advantageous.

[0166] Advantageous TiO₂ pigments are obtainable, for example, under thetradenames T 805 (DEGUSSA) or M 262 (KEMIRA) or M 160 (KEMIRA) or MT 100T (TAYCA).

[0167] Advantageous SiO₂ pigments can be chosen from the series ofhydrophobic pigments marketed under the tradenames AEROSIL (DEGUSSA),for example AEROSIL R 812 or AEROSIL R 972.

[0168] Formulations according to the invention are advantageouslycharacterized by a content of 0.1 to 10% by weight, in particular0.5-5.0% by weight, of hydrophobic inorganic pigments, in each casebased on the total weight of the composition.

[0169] The emulsions according to the invention can in principle fulfilall the cosmetic intended uses which emulsions usually have to fulfil,for example day creams, night creams, hand or body creams, sunscreenformulations, nutrient creams, liposome creams, vitamin creams and soon.

[0170] It is advantageous here to use the formulations according to theinvention both in the field of care cosmetics and in the field ofdecorative cosmetics.

[0171] Where appropriate, however, it is also advantageous to useformulations according to the invention as a carrier substance ofdermatological or topical formulations.

[0172] Some peculiarities and differences in the pre-requisites of O/Wemulsions, O/W microemulsions and O/W/O emulsions according to theinvention will also be briefly discussed below.

[0173] Oils and fats differ, inter alia, in their polarity, which isdifficult to define. It has already been proposed to adopt the surfacetension with respect to water as a measure of the polarity index of anoil or of an oily phase. In this case, the polarity of the oily phase inquestion is greater, the lower the surface tension between this oilyphase and water. According to the invention, the surface tension isregarded as a possible measure of the polarity of a given oil component.

[0174] The surface tension is that force which acts on an imaginary lineof one meter in length in the interface between two phases. The physicalunit for this surface tension is conventionally calculated from therelationship force/length and is usually expressed in mN/m (millinewtonsdivided by meters). It has a positive sign if it endeavours to reducethe interface. In the converse case, it has a negative sign.

[0175] According to the invention, the limit below which an oily phaseis “polar” and above which an oily phase is “non-polar” is regarded as30 mN/m.

[0176] According to the invention, the oily phase for O/W microemulsionsis advantageously chosen from the group consisting of polar oilcomponents which have a polarity of between 10 and 30 mN/m, where itmust be ensured that at least one non-polar oil component is present.

[0177] Advantageous O/W microemulsions are obtained if the oily phase ischosen from the group consisting of polar oil components, particularlypreferably the group consisting of naturally occurring, synthetic orsemisynthetic oil components which have a polarity of between 10 and 20mN/m, where it must be ensured that at least one non-polar oil componentis present.

[0178] It is also advantageous to use polar vegetable oils as polar oilsof the O/W emulsions according to the invention. The vegetable oils canadvantageously be chosen from the group consisting of oils of the plantfamilies Euphorbiaceae, Poaceae, Fabaceae, Brassicaceae, Pedalaceae,Asteraceae, Linaceae, Flacourticaceae and Violales, preferably chosenfrom the group consisting of natural castor oil, wheat germ oil,grapeseed oil, candlenut oil, safflower oil, thistle oil, oil of eveningprimrose and other oils which comprise at least 1.5% by weight oflinoleic acid glycerides.

[0179] In contrast, O/W/O emulsions according to the invention shouldhave only minor amounts of such oil components, and instead of theseshould have chiefly those of which the polarity value is higher than 30mN/m. Naturally occurring, synthetic and semi-synthetic oils, fats andwaxes have similarly proved to be advantageous.

[0180] The addition of electrolytes causes a change in the solubilityproperties of a hydrophilic emulsifier. The hydrophilic emulsifiershaving the structures or properties described above pass through apartial phase inversion in which solubilization of water by the oilyphase occurs, resulting in a stable microemulsion or, in the desiredcase, also a stable O/W/O emulsion.

[0181] The microemulsions according to the invention thereforeadvantageously comprise electrolytes, in particular one or more saltswith the following anions: chlorides, and furthermore inorganic oxoelement anions, and of these in particular sulphates, carbonates,phosphates, borates and aluminates. Electrolytes based on organic anionscan also advantageously be used, for example lactates, acetates,benzoates, propionates, tartrates, citrates and many others. Comparableeffects can also be achieved by ethylenediaminetetraacetic acid andsalts thereof.

[0182] Cations of the salts which are preferably used are ammonium,alkylammonium, alkali metal, alkaline earth metal, magnesium, iron andzinc ions. It does not need mentioning that only physiologicallyacceptable electrolytes should be used in cosmetics. On the other hand,specific medicinal uses of the microemulsions according to the inventionmay at least in principle require the use of electrolytes which shouldnot be used without medical supervision.

[0183] Potassium chloride, sodium chloride, magnesium sulphate, zincsulphate and mixtures thereof are particularly preferred. Salt mixturessuch as occur in the natural salt of the Dead Sea are likewiseadvantageous.

[0184] The concentration of the electrolyte or electrolytes should beabout 0.01-10.0% by weight, particularly advantageously about 0.03-8.0%by weight, based on the total weight of the formulation.

[0185] The emulsifiers of type A can customarily be regarded as O/Wemulsifiers. A content of about 5-10% by weight of the usual W/Oemulsifiers advantageously promotes the formation of O/W/O emulsions,and a content of significantly more than 10% by weight of suchemulsifiers leads to destabilization of the O/W/O emulsions.

[0186] If desired, for the preparation of O/W/O emulsions according tothe invention, it is furthermore advantageous to employ hydrophilicand/or lipophilic gel-forming agents. Although these as a rule do notcontribute towards the formation of multiple droplets, they promote thestability of multiple drops once formed.

[0187] If the pH is to be varied in a preparation process according tothe invention for O/W/O emulsions, in order to bring an otherwisepredetermined system into the phase inversion range, it is advantageousinitially to employ the lowest possible electrolyte concentration in theaqueous phase at the start of the process, and if possible initially toomit this concentration entirely. It is furthermore advantageous foremulsifier A to be initially introduced into the oily phase, for examplefor stearic acid in the concentration range of 0.5-5% by weight, inparticular 2% by weight. The presence of an emulsifier which does notfall under the definition of emulsifier A in the concentration range ofabout 5-10% by weight, in particular about 7% by weight, isadvantageous.

[0188] The pH should advantageously first be varied when the W/Oemulsion has formed, for example by addition of NaOH.

[0189] It lies here within the general expertise of the expert andrequires no inventive step at all to determine the temperature or pHrange in which phase inversion takes place for a given emulsifier or agiven emulsifier system in a given aqueous/oily phase system. As ageneral guideline for the PIT at the usual emulsifier concentrations, atemperature range of about 40-90° C. can be stated. In general, the PITdrops as the emulsifier concentration increases.

[0190] During this process, if desired, the base substances,auxiliaries, additives and/or active compounds customary in cosmetics ormedicine formulations can furthermore be added. It is clear to theexpert at what point in time such substances can be added to the processwithout the properties of the emulsion to be achieved beingsubstantially impaired.

[0191] The following examples are intended to outline the essence of thepresent invention in more detail without limiting the invention.

EXAMPLE 1

[0192] O/W microemulsion % by weight Ceteareth-12 8.00 Cetearylisononanoate 20.00 Cetearyl alcohol 4.00 Uvinul ® T 150 2.00 Parsol ®1789 1.00 Eusolex ® 232 4.80 pH = 7.5 Dyestuffs, perfume, preservativeq.s. Water to 100.00

[0193] The UV filters are dissolved in the oily phase and combined withthe other constituents of the oily phase, after which the mixture ishomogenized, subsequently combined with the aqueous phase and brought toa temperature of 80-85° C. (i.e. into the phase inversion temperaturerange of the system), and the system is then cooled to room temperature(that is to say is brought out of the phase inversion temperature rangeof the system again).

EXAMPLE 2

[0194] O/W microemulsion % by weight Ceteareth-12 12.00 Cetearylisononanoate 20.00 Cetearyl alcohol 6.00 Uvinul ® T 150 2.00 Eusolex ®6300 3.00 Eusolex ® 232 4.80 pH = 7.5 Dyestuffs, perfume, preservativeq.s. Water to 100.00

[0195] The UV filters are dissolved in the oily phase and combined withthe other constituents of the oily phase, after which the mixture ishomogenized, subsequently combined with the aqueous phase and brought toa temperature of 80-85° C. (i.e. into the phase inversion temperaturerange of the system), and the system is then cooled to room temperature(that is to say is brought out of the phase inversion temperature rangeof the system again).

EXAMPLE 3

[0196] O/W microemulsion % by weight Ceteareth-12 8.00 Cetearylisononanoate 20.00 Cetearyl alcohol 4.00 Uvinul ® T 150 4.80 MgSO₄ 3.00Dyestuffs, perfume, preservative q.s. Water to 100.00

[0197] The UV filters are dissolved in the oily phase and combined withthe other constituents of the oily phase, after which the mixture ishomogenized, subsequently combined with the aqueous phase and brought toa temperature of 80-85° C. (i.e. into the phase inversion temperaturerange of the system), and the system is then cooled to room temperature(that is to say is brought out of the phase inversion temperature rangeof the system again).

EXAMPLE 4

[0198] O/W microemulsion % by weight Ceteareth-12 12.00 Cetearylisononanoate 20.00 Cetearyl alcohol 6.00 Uvinul ® T 150 4.80 Parsol ®1789 2.00 TiO₂ 2.00 MgSO₄ 3.00 Dyestuffs, perfume, preservative q.s.Water to 100.00

[0199] The UV filters are dissolved in the oily phase and combined withthe other constituents of the oily phase, after which the mixture ishomogenized, subsequently combined with the aqueous phase and brought toa temperature of 80-85° C. (i.e. into the phase inversion temperaturerange of the system), and the system is then cooled to room temperature(that is to say is brought out of the phase inversion temperature rangeof the system again).

EXAMPLE 5

[0200] O/W microemulsion % by weight Ceteareth-12 8.00 Cetearylisononanoate 10.00 Cetearyl alcohol 4.00 Eusolex ® 232 5.00 Uvinul ® T150 1.00 Parsol ® 1789 4.00 pH = 7.5 Dyestuffs, perfume, preservativeq.s. Water to 100.00

[0201] The UV filters are dissolved in the oily phase and combined withthe other constituents of the oily phase, after which the mixture ishomogenized, subsequently combined with the aqueous phase and brought toa temperature of 80-85° C. (i.e. into the phase inversion temperaturerange of the system), and the system is then cooled to room temperature(that is to say is brought out of the phase inversion temperature rangeof the system again).

EXAMPLE 6

[0202] O/W/O emulsion % by weight Glyceryl isostearate 4.00 Cetearylisononanoate 20.00 Stearic acid 2.00 Uvinul ® T 150 2.00 Parsol ® 17893.00 NaOH to pH 7.0 Dyestuffs, perfume, preservative q.s. Water to100.00

[0203] The UV filters are dissolved in the oily phase and combined withthe remainder of the oily phase. Water is added and the system is heatedto about 40° C. NaOH is added until a pH of 7 is reached, and the systemis then cooled to room temperature.

EXAMPLE 7

[0204] O/W microemulsion % by weight Ceteareth-12 8.00 Cetearylisononanoate 10.00 Mineral oil 10.00 Cetearyl alcohol 4.00 Uvinul ® T150 2.00 Parsol ® 1789 1.00 Eusolex ® 6300 3.00 TiO₂ 4.80 MgSO₄ 3.00Dyestuffs, perfume, preservative q.s. Water to 100.00

[0205] The inorganic micropigment and Uvinul® T 150 are presuspended inthe mineral oil and combined with the remainder of the oily phase, afterwhich the mixture is homogenized and then combined with the aqueousphase and brought to a temperature of 80-85° C. (i.e. into the phaseinversion temperature range of the system), and the system is thencooled to room temperature (that is to say is brought out of the phaseinversion temperature range of the system again).

EXAMPLE 8

[0206] O/W microemulsion % by weight Ceteareth-12 12.00 Cetearylisononanoate 10.00 Mineral oil 10.00 Cetearyl alcohol 6.00 Uvinul ® T150 2.00 Parsol ® 1789 1.00 TiO₂ 4.80 MgSO₄ 3.00 Dyestuffs, perfume,preservative q.s. Water to 100.00

[0207] The inorganic micropigment and Uvinul® T 150 are presuspended inthe mineral oil and combined with the remainder of the oily phase, afterwhich the mixture is homogenized and then combined with the aqueousphase and brought to a temperature of 80-85° C. (i.e. into the phaseinversion temperature range of the system), and the system is thencooled to room temperature (that is to say is brought out of the phaseinversion temperature range of the system again).

EXAMPLE 9

[0208] O/W microemulsion % by weight Ceteareth-12 8.00 Cetearylisononanoate 10.00 Mineral oil 10.00 Cetearyl alcohol 4.00 TiO₂ 5.00MgSO₄ 3.00 Dyestuffs, perfume, preservative q.s. Water to 100.00

[0209] The inorganic micropigment is presuspended in the mineral oil andcombined with the remainder of the oily phase, after which the mixtureis homogenized and then combined with the aqueous phase and brought to atemperature of 80-85° C. (i.e. into the phase inversion temperaturerange of the system), and the system is then cooled to room temperature(that is to say is brought out of the phase inversion temperature rangeof the system again).

EXAMPLE 10

[0210] O/W/O emulsion % by weight Glyceryl isostearate 5.00 Mineral oil25.00 Stearic acid 2.00 TiO₂ 2.00 NaOH to pH 7.0  Dyestuffs, perfume,preservative q.s. Water to 100.00

[0211] The inorganic micropigment is dispersed in the oily phase. Wateris added and the system is heated to about 40° C. NaOH is added until apH of 7 is reached, and the system is then cooled to room temperature.

EXAMPLE 11

[0212] O/W/O emulsion % by weight Polyglyceryl 2-polyhydroxystearate7.00 Cetearyl isononanoate 12.50 Mineral oil 12.50 Stearic acid 2.00TiO₂ 2.00 NaOH to pH 7.0  Dyestuffs, perfume, preservative q.s. Water to100.00

[0213] The inorganic micropigment is presuspended in the mineral oil andcombined with the remainder of the oily phase. Water is added and thesystem is heated to about 40° C. NaOH is added until a pH of 7 isreached, and the system is then cooled to room temperature.

EXAMPLE 12

[0214] O/W/O emulsion % by weight Polyglyceryl 2-polyhydroxystearate5.00 Cetearyl isononanoate 12.50 Mineral oil 12.50 Stearic acid 2.00TiO₂ 2.00 NaOH to pH 7.0  Dyestuffs, perfume, preservative q.s. Water to100.00

[0215] The inorganic micropigment is dispersed in the oily phase. Wateris added and the system is heated to about 40° C. NaOH is added until apH of 7 is reached, and the system is then cooled to room temperature.

EXAMPLE 13

[0216] O/W microemulsion % by weight Polyglyceryl 2-polyhydroxystearate2.00 Cetearyl isononanoate 12.50 Mineral oil 12.50 Stearic acid 2.00TiO₂ 2.00 NaOH to pH 7.0  Dyestuffs, perfume, preservative q.s. Water to100.00

[0217] The inorganic micropigment is presuspended in the mineral oil andcombined with the remainder of the oily phase. Water is added and thesystem is heated to about 40° C. NaOH is added until a pH of 7 isreached, and the system is then cooled to room temperature.

EXAMPLE 14

[0218] O/W microemulsion % by weight Ceteareth-12 8.00 Cetearylisononanoate 20.00 Cetearyl alcohol 4.00 Eusolex ® 232 4.80 MgSO₄ 3.00pH = 5.0  Dyestuffs, perfume, preservative q.s. Water to 100.00

[0219] The constituents of the oily phase are combined and homogenizedand then combined with the aqueous phase and brought to a temperature of80-85° C. (i.e. into the phase inversion temperature range of thesystem), and the system is then cooled to room temperature (that is tosay brought out of the phase inversion temperature range of the systemagain).

EXAMPLE 15

[0220] O/W microemulsion % by weight Ceteareth-12 12.00 Cetearylisononanoate 20.00 Cetearyl alcohol 6.00 Eusolex ® 232 4.80 Parsol ®1789 2.00 MgSO₄ 3.00 pH = 5.0  Dyestuffs, perfume, preservative q.s.Water to 100.00

[0221] The constituents of the oily phase are combined and homogenizedand then combined with the aqueous phase and brought to a temperature of80-85° C. (i.e. into the phase inversion temperature range of thesystem), and the system is then cooled to room temperature (that is tosay brought out of the phase inversion temperature range of the systemagain).

EXAMPLE 16

[0222] O/W microemulsion % by weight Ceteareth-12 8.00 Cetearylisononanoate 10.00 Mineral oil 10.00 Cetearyl alcohol 4.00 Uvinul ® T150 4.80 MgSO₄ 3.00 Dyestuffs, perfume, preservative q.s. Water to100.00

[0223] The Uvinul® T 150 is presuspended in the mineral oil and combinedwith the remainder of the oily phase, after which this is homogenizedand then combined with the aqueous phase and brought to a temperature of80-85° C. (i.e. into the phase inversion temperature range of thesystem), and the system is then cooled to room temperature (that is tosay brought out of the phase inversion temperature range of the systemagain).

EXAMPLE 17

[0224] O/W microemulsion % by weight Ceteareth-12 12.00 Cetearylisononanoate 10.00 Mineral oil 10.00 Cetearyl alcohol 6.00 Eusolex ®6300 2.00 Parsol ® 1789 0.50 Uvinul ® T 150 4.80 MgSO₄ 3.00 Dyestuffs,perfume, preservative q.s. Water to 100.00

[0225] The Uvinul® T 150 is presuspended in the mineral oil and combinedwith the remainder of the oily phase, after which this is homogenizedand then combined with the aqueous phase and brought to a temperature of80-85° C. (i.e. into the phase inversion temperature range of thesystem), and the system is then cooled to room temperature (that is tosay brought out of the phase inversion temperature range of the systemagain).

EXAMPLE 18

[0226] O/W microemulsion % by weight Ceteareth-12  8.00 Cetearylisononanoate  10.00 Cetearyl alcohol  4.00 Eusolex ® 232  5.00 Uvinul ®T 150  1.00 MgSO₄  3.00 pH =  5.0 Dyestuffs, perfume, preservative q.s.Water to 100.00

[0227] The constituents of the oily phase are combined and homogenizedand then combined with the aqueous phase and brought to a temperature of80-85° C. (i.e. into the phase inversion temperature range of thesystem), and the system is then cooled to room temperature (that is tosay brought out of the phase inversion temperature range of the systemagain).

EXAMPLE 19

[0228] O/W microemulsion % by weight Ceteareth-12  8.00 Cetearylisononanoate  10.00 Mineral oil  10.00 Cetearyl alcohol  4.00 Uvinul ® T150  5.00 MgSO₄  3.00 Dyestuffs, perfume, preservative q.s. Water to100.00

[0229] The Uvinul® T 150 is presuspended in the mineral oil and combinedwith the remainder of the oily phase, after which this is homogenizedand then combined with the aqueous phase and brought to a temperature of80-85° C. (i.e. into the phase inversion temperature range of thesystem), and the system is then cooled to room temperature (that is tosay brought out of the phase inversion temperature range of the systemagain).

EXAMPLE 20

[0230] O/W/O emulsion % by weight Glyceryl isostearate  5.00 Mineral oil 25.00 Stearic acid  2.00 Uvinul ® T 150  2.00 NaOH to pH  7.0Dyestuffs, perfume, preservative q.s. Water to 100.00

[0231] The Uvinul® T 150 is dispersed in the oily phase. Water is addedand the system is heated to about 40° C. NaOH is added until a pH of 7is reached, and the system is then cooled to room temperature.

EXAMPLE 21

[0232] O/W/O emulsion % by weight Polyglyceryl 2-polyhydroxystearate 7.00 Cetearyl isononanoate  12.50 Mineral oil  12.50 Stearic acid  2.00Uvinul ® T 150  2.00 Parsol ® 1789  2.00 Eusolex ® 232  2.00 NaOH to pH 7.0 Dyestuffs, perfume, preservative q.s. Water to 100.00

[0233] The UV filter substances are presuspended in the mineral oil andcombined with the remainder of the oily phase. Water is added and thesystem is heated to about 40° C. NaOH is added until a pH of 7 isreached, and the system is then cooled to room temperature.

EXAMPLE 22

[0234] O/W/O emulsion % by weight Polyglyceryl 2-polyhydroxystearate 5.00 Cetearyl isononanoate  12.50 Mineral oil  12.50 Stearic acid  2.00Eusolex ® 232  2.00 Uvinul ® T 150  2.00 Eusolex ® 6300  2.00 Parsol ®1789  1.00 NaOH to pH  7.0 Dyestuffs, perfume, preservative q.s. Waterto 100.00

[0235] The UV filter substances are dispersed in the oily phase. Wateris added and the system is heated to about 40° C. NaOH is added until apH of 7 is reached, and the system is then cooled to room temperature.

EXAMPLE 23

[0236] O/W microemulsion % by weight Polyglyceryl 2-polyhydroxystearate 2.00 Cetearyl isononanoate  12.50 Mineral oil  12.50 Stearic acid  2.00Uvinul ® T 150  2.00 NaOH to pH  7.0 Dyestuffs, perfume, preservativeq.s. Water to 100.00

[0237] The Uvinul® T 150 is presuspended in the mineral oil and combinedwith the remainder of the oily phase. Water is added and the system isheated to about 40° C. NaOH is added until a pH of 7 is reached, and thesystem is then cooled to room temperature.

1. O/W emulsions, in particular O/W microemulsions, or O/W/O emulsionsor O/W/O′ emulsions comprising an aqueous phase, if appropriate,customary water-soluble or -dispersible substances, an oily phase, atleast one emulsifier (emulsifier A) chosen from the group of emulsifiershaving the following properties their lipophilicity either depends onthe pH such that the lipophilicity is increased or decreased by raisingor lowering the pH, it being unimportant which of the two possiblechanges in lipophilicity is effected by raising or lowering the pH,and/or their lipophilicity depends on the temperature such that thelipophilicity increases with increasing temperature and theirhydrophilicity, increases with decreasing temperature, and furthermore,if appropriate, further substances which are soluble or dispersable inthe oily phase, including, preferably, those chosen from the group ofemulsifiers which do not fall under the definition of emulsifier A, inparticular those which chiefly act as W/O emulsifiers.
 2. Process forthe preparation of O/W emulsions, in particular O/W microemulsions, orO/W/O emulsions or O/W/O′ emulsions, characterized in that an aqueousphase, if appropriate, customary a water-soluble or -dispersiblesubstances, an oily phase and at least one emulsifier (emulsifier A)chosen from the group of O/W emulsifiers having the following propertiestheir lipophilicity depends on the PH such that the lipophilicity isincreased or decreased by raising or lowering the pH, it beingunimportant which of the two possible changes in lipophilicity iseffected by raising or lowering the pH, and if appropriate, theirlipophilicity additionally depends on the temperature such that thelipophilicity increases with increasing temperature and theirhydrophilicity increases with decreasing temperature, and furthermore,if appropriate, further substances which are soluble or dispersible inthe oily phase, including, preferably, those chosen from the group ofemulsifiers which do not fall under the definition of emulsifier A, arebrought together and a mixture is formed, with agitation, such that bysuitable choice of the parameters chosen from the group consisting ofpH, temperature and the concentration or concentrations of at least oneof the emulsifiers chosen, this mixture is brought into the phaseinversion range in which W/O emulsions are converted into O/W emulsions,by varying at least one parameter chosen from the group consisting ofpH, temperature and the concentration or concentrations of at least oneof the emulsifiers chosen, the W/O emulsion formed is brought out of thephase inversion range in which a W/O emulsion formed is converted intoan O/W emulsion, whereupon an O/W emulsion or O/W microemulsion isproduced, if appropriate, by suitable choice of the frameworkconditions, another phase inversion to give an O/W/O emulsion isinitiated, if appropriate, the mixture is subjected to furtherprocessing steps, in particular one or more homogenizing steps. 3.Process according to claim 2 for the preparation of O/W/O emulsions,characterized in that the oily phase content is greater than about 15%by weight, in particular greater than about 20% by weight, based on thetotal weight of the formulation, more than about 5% by weight, inparticular about 5-10% by weight, of an additional emulsifier which actsas a W/O emulsifier at room temperature is present, and/or the oilyphase has a low content of polar oils or is essentially free from suchoils.
 4. Process according to claim 2 for the preparation of O/Wmicroemulsions, characterized in that the oily phase content is lessthan about 20% by weight, in particular less than about 15% by weight,based on the total weight of the formulation, less than about 5% byweight of an additional emulsifier which acts as a W/O emulsifier atroom temperature is present, and/or the oily phase has a high content ofpolar oils.
 5. O/W/O emulsions or O/W microemulsions according to claim1, characterized in that emulsifier A is chosen from the groupconsisting of sorbitan esters and sucrose esters, in particular ofbranched and unbranched alkyl esters and alkenyl esters having carbonchains of 4-24 carbon atoms, preferably sorbitan stearate, sorbitanoleate, glycerylsorbitan stearate, sucrose monostearate, sucrosemonolaurate and sucrose palmitate, of monoglycerol monocarboxylic acidmonoesters and of di- and triglycerol monocarboxylic acid monoesters,and furthermore triglyceryl diisostearate, isostearyldiglycerylsuccinate, diglyceryl sesquiisostearate, triglycerylpolyhydroxystearate, cetearyl isononanoate anddicocoyl-pentaerythrityldistearyl citrate, and furthermore the methiconecopolyols, cyclomethicone copolyols, alkylmethicone copolyols,laurylmethicone copolyol and cetyldimethicone copolyol, as well as fromthe group consisting of branched or unbranched alkylmonocarboxylicacids, alkenylmonocarboxylic acids and alkylenedicarboxylic acids having4 to 30 carbon atoms, in particular stearic acid, oleic acid, succinicacid, hexanoic acid (caproic acid), heptanoic acid (oenanthic acid),octanoic acid (caprylic acid), nonanoic acid (pelargonic acid), decanoicacid (capric acid), undecanoic acid, undecenoic acid (undecylenic acid),dodecanoic acid (lauric acid), tridecanoic acid, tetradecanoic acid(myristic acid), pentadecanoic acid, hexadecanoic acid (palmitic acid),heptadecanoic acid (margaric acid), octadecanoic acid (stearic acid),isostearic acid and behenic acid and cosmetically or pharmaceuticallyacceptable salts thereof, in particular of the alkali metal, ammonium,monoalkylammonium, dialkylammonium, trialkylammonium andtetraalkylammonium salts.
 6. O/W/O emulsions or O/W microemulsionsaccording to claim 1, characterized in that the emulsifier A oremulsifiers A is or are present in concentrations of 0.01-20% by weight,preferably 0.05-10% by weight, particularly preferably 0.1-5% by weight,in each case based on the total weight of the composition.